In this quick tutorial, Lead Character Artist, Gavin Goulden will share with you how he defines seams using UV islands in ZBrush, which are then used to define seams
in clothing!

When sculpting clothing, it's very easy for things to get messy fast. Details can bleed over into areas that they shouldn't, lines can get wobbly, and can become inconsistent throughout the model.

One step that I like to take to preserve this information is to create Polygroups that preserve landmarks within my sculpture, using UV islands made in my base mesh. This can help mark seams, isolate overlapping areas, keep areas easy to mask out, and ultimately helps keep your model nice and organized for an easier workflow.

Using Polygroups in this sculpt not only helped keep information isolated and crisp, but also helped managing bakes later for the game resolution asset

Creating Polygoups using UV islands

In order to create Polygroups based on UVs, you will need to create UV islands that resemble sections of your model that you would like to isolate. Generally, I like to follow natural seams in the clothing, which help me define them in the sculpt by hiding sections or masking them out.

How you create the islands doesn't matter – the UV layout doesn't need to be something you would use for painting – but what is important is that you keep the islands continuous. Any polygon left out of an island will create a new Polygroup. In ZBrush, with your SubTool selected, navigate to SubTools > Autogroups with UV. With the wireframe enabled, you can see the new SubTools that have been created.

In this example, you can see the difference between a model with 1 Polygroup versus a model with multiple Polygroups. You can see on the right how this model is better organized for sculpting

Pro tip: Using Polygroups to isolate areas

After the Polygroups have been created, you can Ctrl+Shift-click onto a group to hide it. This allows you to create masks and isolate areas to define nice, crisp seams and avoid having sculpting information bleed over from one island to another – another cool way to help pin points of tension when sculpting clothes!

Use Polygroups to isolate areas to avoid having sculpting information bleed across seams. This helps keep information crisp and helps avoid 'blobby' sculptures